feat: tool timeout auto-retry, file tree attachment, force stop button

- Add configurable tool timeout with auto-retry: when a tool exceeds the
  timeout threshold, abort and send a follow-up message asking Claude to
  try a different approach
- Add "+" button on file tree items to attach files directly to chat
  input via new /api/files/raw endpoint and custom event bridge
- Add force stop button in streaming status bar when tool runs >90s,
  with warning indicators at 60s
- Improve doc preview markdown rendering (padding, list indentation)
- Bump version to 0.10.0

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/types/index.ts

@@ -305,6 +305,7 @@ export type SSEEventType =
   | 'tool_use'           // tool invocation info
   | 'tool_result'        // tool execution result
   | 'tool_output'        // streaming tool output (stderr from SDK process)
+  | 'tool_timeout'       // tool execution timed out
   | 'status'             // status update (compacting, etc.)
   | 'result'             // final result with usage stats
   | 'error'              // error occurred
@@ -432,4 +433,5 @@ export interface ClaudeStreamOptions {
   abortController?: AbortController;
   permissionMode?: string;
   files?: FileAttachment[];
+  toolTimeoutSeconds?: number;
 }